Fifty-two species are placed in the Bactrocera dorsalis complex in Asia, eight of which are considered of economic importance. Twelve species are revised and the following forty new species described: Bactrocera atrifemur, B. bimaculata, B. carambolae, B. cibodasae, B. collita, B. floresiae, B. fulvifemur, B. fuscitibia, B. gombokensis, B. indonesiae, B. infulata, B. irvingiae, B. kanchanaburi, B. kandiensis, B. kinabalu, B. lateritaenia, B. latilineola, B. lombokensis, B. makilingensis, B. malaysiensis, B. melastomatos, B. merapiensis, B. minuscula, B. neocognata, B. neopropinqua, B. osbeckiae, B. papayae, B. penecognata, B. philippinensis, B. pyrifoliae, B. quasipropinqua, B. raiensis, B. sembaliensis, B. sulawesiae, B. sumbawaensis, B. thailandica, B. unimacula, B. usitata, B. verbascifoliae and B. vishnu. A key to species within the complex is presented. Information is given on location of type specimens, host-plants, attractant records and geographic distribution. Lectotypes are designated for B. dorsalis (Hendel), B. mangiferae (Cotes) (a synonym of B. zonata (Saunders)) and B. pedestris (Bezzi).

In response to field pyrethroid failures against Helicoverpa armigera (Hübner) in early 1983, an insecticide resistance management (IRM) strategy was introduced for insect control in summer crops in eastern Australia. The aims of this strategy were to contain the pyrethroid resistance problem, to prevent re-selection of historical endosulfan resistance (both curative IRM) and to avoid any future problems with organophosphate/carbamate resistance (preventative IRM). An alternation strategy was adopted which was based on the rotation of unrelated chemical groups on a per generation basis, along with a strong recommendation for the use of ovicidal mixtures. These chemical countermeasures were then integrated with other non-chemical control methods (biological and cultural) into a workable integrated pest management programme. The restrictions were applied to all Helicoverpa armigera susceptible crops (including cereals, oilseeds, grain legumes, tomatoes, tobacco and cotton) and even to other co-incident pest species. From its inception, compliance with the voluntary strategy has been exceptional.

The Philippine species of Atherigona are revised for the first time. Summaries of previous taxonomic and biological work are presented, and keys for the identification of the species are given. Notes or descriptions are provided for each species, together with illustrations of the male and female terminalia and of other diagnostic features. A full bibliography for the Philippines completes the paper. Forty-four species have been identified and named, of which thirty-five are newly recorded from the Philippines, and a further twenty-nine species have been diagnosed but not described. Eleven new species are described: Atherigona (Acritochaeta) cristata, A. (A), dahlia, A. (A.) lamellifera, A. (A.) philema, A. (A) strigula, A. (A.) tenuipes; Atherigona (Atherigona) ambulans, A. (A.) libra, A. (A.) osculata, A. (A.) pica and A. (A.) savia. Seven new synonyms are established, based on type-examinations: A. nigripes Stein, 1900 (synn. n.: longiseta Malloch, 1924; pilimana Hennig, 1952; ferrari Pont, 1986); A. unguicauda Malloch, 1928 (syn. n.: hirtitarsis Pont, 1986); A. orbicularis Fan & Liu, 1982 (syn. n.: occulta Pont, 1986); A. maculigera Stein, 1910 (syn. n.: crassiseta Stein, 1915); A. seticauda Malloch, 1926 (syn. n.: dorsovittata Malloch, 1928).

Resistance to endosulfan and pyrethroids in Helicoverpa armigera in Australia was shown to be due to multiple rather than cross resistance. The independence of the endosulfan and pyrethroid resistance mechanisms vindicates the sequential use of these two groups in Stages I and II of the insecticide resistance management strategy, respectively. Within the cyclodienes, greatest resistance occurred to dieldrin with lower order cross resistance to endosulfan and endrin. Male and female moths expressed cyclodiene resistance equally.

The dual insecticide ± synergist discriminating dose technique proved highly successful in determining the relative importance of pyrethroid resistance mechanisms present in field populations of Helicoverpa armigera, without the problems of alternative techniques. Synergist pre-treatment proved unnecessary therefore allowing use of the more convenient and labour efficient discriminating dose pre-mix.

Oxidative metabolic detoxification, probably via a polysubstrate monooxygenase system, was the major pyrethroid resistance mechanism in both larval and adult H. armigera. Residual piperonyl butoxide insensitive resistance (presumably nerve insensitivity, possibly acting in combination with the penetration resistance factor) was also present but at a low level. This latter resistance mechanism was expressed in larvae but moths appeared to express only weak phenotypic resistance. The predominant pyrethroid resistance mechanism employed by insects is discussed in relation to their feeding habit. The tenet that nectar feeding adult Lepidoptera are unable to express metabolic pyrethroid resistance is challenged.

Unrestrained pre-strategy pyrethroid selection pressure on sequential generations resulted in selection for elevated levels of kdr type nerve insensitivity and possibly even super kdr. Restriction of pyrethroid selection pressure to one generation per season favoured selection of the oxidative over the nerve insensitivity resistance mechanism. Two possibly complementary explanations are put forward for this; differential genetic dominance (semidominant oxidative mechanism versus recessive nerve insensitivity) and/or selection in more than one life stage (moths and larvae for the oxidative mechanism versus predominantly larvae only for the nerve insensitivity mechanism). It is suggested that insecticide resistance management strategies should be designed to avoid selection of elevated levels of the intractable nerve insensitivity resistance mechanism whereas low levels of this mechanism (normal kdr) are not considered difficult to manage. The demonstration that the strategy has favoured selection of the more amenable oxidative resistance mechanism invites the opportunity to develop possible chemical countermeasures.

The structural requirements for designing a resistance breaking pyrethroid to overcome oxidative metabolic pyrethroid resistance in Helicoverpa armigera were studied. A range of pyrethroid structures were tested on a well defined pure breeding pyrethroid resistant strain of H. armigera (homozygous for a metabolic detoxification mechanism fully suppressible by piperonyl butoxide, presumably via a microsomal monooxygenase system). Highest resistance factors were to the ester bonded phenoxybenzyl alcohol pyrethroids, particularly to those with an aromatic acid moiety. Changes to the alcohol moiety alone could overcome most, if not all, resistance. Simple benzyl alcohols were the most effective followed by cyclopentenolones and a methylated biphenyl alcohol. However, the benzylfurylmethyl alcohol (bioresmethrin) was not effective. The incorporation of a synergophore grouping into the alcohol moiety was fully effective for Scott's Py III (methylenedioxyphenyl) and prallethrin (propynyl) but only partially effective for tetramethrin (N-alkyl). Changes to the acid moiety had little effect except for the incorporation of a synergophore methylenedioxyphenyl grouping (Cheminova I) which was just as effective as for the same insertion in the alcohol moiety. The change to a central ether bond from the conventional ester bond lowered resistance. Reversion to an unsubstituted alpha carbon analogue from the conventional alpha cyano group also lowered resistance.

Piperonyl butoxide (Pbo) had little effect on pyrethroid toxicity in the susceptible strain except for the single isomers deltamethrin and esfenvalerate. However, it was more than fully effective in overcoming resistance and actually reduced resistance factors to significantly below one in the resistant strain. This indicated the possibility that Pbo could be acting both as a classical monooxygenase inhibitor and a preferential penetration synergist in resistant larvae.

Partial or full resolution of racemic mixtures had minimal impact on increasing toxicity in the susceptible strain. However, partially or fully resolved isomers were clearly much more toxic on resistant strains, indicating a possible blocking effect of the inactive isomers during the toxication process with the higher pyrethroid doses applied to resistant larvae. Cis isomers had only slightly higher resistance factors than trans isomers.

Seven fully effective resistance breaking pyrethroids were identified in this study and one of these (the simple benzyl alcohol, Series Two) was shown to be equally effective on both adults and larvae of H. armigera. It was also shown to work equally well on laboratory or field material and gave results similar to a pyrethroid/Pbo combination. However, none of the resistance breakers identified so far are able to satisfy all of the requirements necessary for an ideal resistance breaking pyrethroid (i.e. good resistance breaking activity at low rates, photostability, residual activity similar to current pyrethroids and safety to mammals). Factors acting against the possible commercialization of successful resistance breaking compounds are discussed.

Sixty-five synergists and seven solvents were tested on larvae of a pure breeding pyrethroid resistant strain of Helicoverpa armigera (homozygous for a metabolic detoxification mechanism fully suppressible by piperonyl butoxide (Pbo), presumably via a microsomal monooxygenase system). The methylenedioxyphenyl and acetylenic compounds were the most effective synergists with moderate activity from some organophosphate compounds, particularly the N-alkyl phthalimidomethyl phosphorodithioate, phosmet. All the other compounds tested were either ineffective or only marginally effective including the majority of organophosphates (12 out of 18 tested), pyrethroid analogues, N-alkyls, esterase and glutathione transferase inhibitors, various nitrogen heterocycles, juvenile hormone and analogues, formamidines, organochlorines, anti-oxidants and kojic acid. The most promising synergists indicated for further evaluation were synthetic analogues of Pbo, phosmet, propargite and possibly also fenthion, phosalone, azinphos-ethyl, pyrazophos and kinoprene. All solvents (except dodecane) had no impact on improving kill, indicating that the mode of action of Pbo and the other synergists in this study is principally true biochemical inhibition and not quasi-synergism (improved penetration). Dodecane marginally improved kill in the resistant but not the susceptible strain, indicating some preferential penetration synergism in the resistant strain.

A number of trials with Pbo were designed to facilitate the development of this synergist for commercial field use within the Australian IRM strategy. From these, it was found that: 1. A set rate of Pbo should be used, irrespective of the activity of the accompanying pyrethroid. 2. Residual activity of Pbo is poor (less than 50% of initial activity by two days post spray) but that this could be partially overcome by increasing the rate. 3. Straight Pbo applied onto a weathered pyrethroid deposit could restore control but only temporarily and would probably be of little practical field use. 4. No difference in residual activity could be found between the four formulations of Pbo tested. The synthetic analogue PBX was slightly less intrinsically active than the natural product (Pbo) but when tested in the field against Pbo at the same rate, was equivalent in efficacy to both the standard commercial and research Pbo formulations.

In order to preserve the long-term effectiveness of Pbo as a pyrethroid synergist within the Australian IRM strategy, an optimal use strategy (based on synergist rotation within the present insecticide rotation scheme) is proposed.

Both pyrethroid and endosulfan resistant Helicoverpa armigera larvae were shown to have marginally longer development times. Pyrethroid resistant larvae were slower developers often requiring an extra moult before ultimately pupating to the same size pupa as susceptibles. There were no differences between pyrethroid resistant and susceptible pupal development times (male or female). Laboratory and field competition studies could demonstrate no selective advantage for either pyrethroid resistant or susceptible larvae or prepupae. Thus it would seem that the slightly longer larval development times do not manifest as significant biological deficits. This helps explain the gradually deteriorating pyrethroid resistance situation documented during evaluation of the Australian insecticide resistance management (IRM) strategy. There was no evidence of the selection of fitness modifiers (co-adaptation) to overcome the slower development of either pyrethroid or endosulfan resistant larvae. Endosulfan fitness disadvantages were not sufficiently researched in this study to discount the possibility of a fitness deficit contributing to the much more successful management of endosulfan resistance.

Pyrethroids applied to flowering sorghum, at either the low midge rate or the higher Helicoverpa rate (20 g and 100 g fenvalerate a.i./ha, respectively), caused selective mortality of Helicoverpa armigera larvae and resulted in differential selection for resistance. This finding vindicated the original strategy decision to apply the same temporal restrictions on pyrethroid use for sorghum midge, Contarinia sorghicola, as those for H. armigera.